What do you think has spurred the boom in consumer electronics? Maybe it’s faster processors the size of a stamp or low power wide area networks. I, personally, think the the Internet of Things boom and the recent rise in machine learning technology comes from a different sources, batteries. Batteries inform the design of many embedded systems, but none more than the electric vehicle (EV). They are also critical for gasoline powered cars with advanced driver assistance systems (ADAS). Even as fuel based cars become more electrified they will need batteries with high energy densities at a reasonable price. This is why Tesla’s innovation in the portable energy department is so important. Tesla has been using a normal kind of Lithium Ion (Li-Ion) battery in their cars for years now, but even how they use that battery is novel. Recently, they have developed a new Li-Ion battery with a different form factor for their cars in the future. This approach to battery tech will pave the way for smarter cars, regardless of whether they are gas or electric.

The Importance of Batteries

Obviously, batteries are important for electric vehicles. Not only do their storage rates matter for vehicle range, but their discharge rates govern acceleration and their volatility affects driving safety. In traditional cars, batteries are a bit less complicated and have been considered less important. They power your car’s electronic systems, but as long as your battery isn’t dead, who cares how it works. However, as vehicles become increasingly electrified with chips and sensors they’ll need more electrical storage and that storage will need to use less physical space. That’s where Li-Ion batteries come in.

One of the main hurdles that ADAS enabled cars have to overcome is power hungry electronic sensors and processors. Some companies, like Nvidia, are now targeting this low power market and are making integrated circuits (ICs) for the future of driving. However, no matter how low power these chips are, they will still need quite a bit of juice. Lead acid batteries have reached their capacity limit. If you want more storage you’ll need a larger battery. Li-Ion batteries on the other hand, have not. Cars are going to need more energy storage and they’ll need advanced batteries like the ones Telsa is developing to get it.

The main reason we can’t increase the size of lead acid batteries in cars is a lack of physical space. Cars are becoming crowded. Some ADAS systems come with so much wiring that they’re taking up all available space inside the car and weighing it down. Adding another 10 pounds of battery is not an option. Li-Ion cells have over 3 times the gravimetric energy density of lead acid cells. That means you can get the same storage capacity for around a 3rd of the weight. Smaller, lighter, battery packs will help us move into the autonomous age of vehicles.

The 18650 is a very common battery form factor.

Tesla and the 18650

As an EV company Tesla is heavily invested in battery technology. They also have to compete with the prices of traditional cars, meaning they’re trying to save every penny during production. Those pressures led Tesla to an unorthodox battery solution for their products. Instead of large, specially designed batteries to power their cars they use lots of regular Li-Ion batteries. Using commercially available batteries saves Tesla money in design, development, and testing. The batteries do have to be slightly modified in order to optimized them for cars, but those changes are significantly cheaper than designing a large, unique, battery.

Tesla uses thousands of small “18650” format Li-Ion cells in their cars. 18650 simply stands for the physical dimensions of the batteries, 18 mm x 65 mm. These small batteries are combined to form one large battery that can be used to run an entire car. The most notable change that Tesla makes to these batteries is in terms of safety. As these batteries are generally used in smaller numbers in consumer electronics, they each need their own individual safety mechanisms. However, when combined together you don’t need individual failsafes, just one overarching one. So, Tesla removes the safety systems on each individual cell, adds in battery management systems to control the batteries, and puts in some fireproofing. This allows them to lose some weight off of each small battery and still have a safe car.

Here’s hoping we see these batteries at work in future Tesla cars. Editorial credit: Kekyalyaynen / Shutterstock.com

The Next Step

As great as the 18650 battery has been for Tesla all good things must come to an end. To that end Tesla has built a giant factory to produce its own novel small cells for its products. These cells promise to be a next step in Li-Ion technology and will help Tesla achieve increasingly higher energy densities in its cars.

What would those kinds of batteries mean for the automotive world? We may not find out for a little while, as Tesla has announced they don’t plan to use the 2170 in their Models S and X right now. Instead they’re going to be used in Tesla’s solar home storage system, the Powerwall and Powerpack, and hopefully in the Model 3. New batteries with higher energy densities can either increase the range of EVs or decrease their cost, or if you believe Musk, both. In terms of traditional vehicles new battery technology presents a solution to the power problem for ADAS systems. Smaller, lighter, batteries leave more room for chips and sensors. Conversely if you keep the battery’s weight and space budget in a car, you could provide more energy storage to run ADAS systems. Regardless of whether you have gasoline or electricity powering your car, you’re going to need better batteries.